US Rep. Jesse Jackson, Jr., D-IL, speaks to reporters following a Democratic Caucus on August 1, 2011 at the US Capitol in Washington, DC. With time running out before the August 2 deadline to reach an agreement on the debt ceiling, Congress is working to strike a deal that would avoid a potential federal default next week. AFP PHOTO / Karen BLEIER (Photo credit should read KAREN BLEIER/AFP/Getty Images)

CHICAGO (AP) — U.S. Rep. Jesse Jackson Jr.’s office announced Monday in a news release that the congressman has been on a medical leave of absence since June 10 and is being treated for exhaustion.

The statement, just three sentences long, did not provide further details, including how long he would be away. The statement also said his offices will remain open for constituent services.

“I don’t know how long he’ll be out of action,” said Frank Watkins, Jackson’s spokesman.

Jackson’s congressional colleagues noted his absence on the House floor last week but did not know why he was gone, said U.S. Rep. Danny Davis, a Chicago Democrat.

Jackson first won office in 1995 and represents Illinois’ 2nd District, which includes neighborhoods on Chicago’s South Side and south suburbs.

He is under investigation by the House Ethics Committee, facing allegations that he was involved in discussions about raising money for then-Illinois Gov. Rod Blagojevich’s campaign in exchange for an appointment to President Barack Obama’s old U.S. Senate seat.

Jackson also allegedly directed a fundraiser to buy plane tickets for a woman described by an associate as Jackson’s “social acquaintance.” The issue came up on the campaign trail during Jackson’s 2010 re-election and in the March primary, which the Democrat easily won. Jackson has since called it a personal matter that he and his wife have dealt with privately.

Jackson has not been charged. He has repeatedly denied wrongdoing and insists he will be vindicated.

His father, the Rev. Jesse Jackson, was out of the country Monday and declined to comment on the matter. Messages left for Jesse Jackson Jr.’s wife, Chicago Alderman Sandi Jackson, were not immediately returned.